1. Field of the Invention
The present invention relates to a stackable, open-top crate for holding and transporting objects.
2. Background Art
Generally, crates for carrying objects such as milk containers are molded from plastic to form an open-top box having four side walls integrated with a bottom surface. A partial cross section representative of a conventional crate is shown in FIG. 1. As shown, a side wall 10 is integrally formed with a bottom surface 12. An underside portion 14 of the bottom surface is typically formed with a drag rail 16 around the periphery of the underside portion. The drag rail functions to raise the bottom of the crate off a floor surface, as well as to provide a positioning and holding feature when stacked arranged to nest within the top of another crate to facilitate stacking thereof. The latter function is performed by positioning the drag rail of one crate so as to fit within the inner upper edge of another crate, thus positioning the crate directly above for maximum stability. When stacked with another crate, the drag rail provides alignment and stability of the stacked formation.
In addition, crates have been molded or formed so that the interior side walls possess a taper or draft (denoted by an outwardly curved or angled inner surface 18 in FIG. 1) to maximize the dimension of the upper inner edge surface of the crate and improve manufactureability. In other words, the side walls are formed so that the internal width dimension at the upper inner edge surface of the crate is increased relative to the internal width at the bottom surface. Increasing the dimension of the upper inner edge of the crate eases loading and unloading of products to and from the crate.
However, such increased dimensioning of the upper edge also increases the clearance between the outside of the drag rail of a stacked crate and the upper edge and retaining face of the lower crate. As a consequence, the lateral tolerance between stacked crates is too great, thereby potentially compromising the stability and alignment of a stack of crates.
In addition, the drag rail of known crate designs is spaced away from the outer edge of the crate to facilitate nesting within another crate when stacked thereon. This spacing is denoted by reference number 20 in FIG. 1. Because of the spaced relationship, any vertical load forces F placed on the side walls can not be directly transferred down to the floor surface because the drag rail is not positioned in vertical alignment with the side walls. Instead, the drag rail operates as a fulcrum. This undesirably results in added stresses in the bottom area “fulcrum” due to its inability to resist top load compression. The added stresses result in deflection and potential unbalancing of a stacked formation.
Therefore, a need exists for a crate that cost effectively improves stability and stacking fit while still providing an enlarged opening for ease of product loading and unloading.